The present invention relates to a hoisting/pulling device, and more particularly to a hoisting/pulling device which can make the whole device compact and lightweight and can reduce the number of parts and the man-hours for machining and assembling the device.
The support structure of reduction gears and the structure of a load gear in a conventional hoisting/pulling device are explained in conjunction with FIG. 5 and FIG. 6.
In these drawings, numeral 21 indicates a frame for a load sheave bearing and reduction gear bearings, numeral 22 indicates a load sheave, numeral 23 indicates a load gear, numeral 24 indicates a pinion gear, numeral 25 indicates reduction gears which are meshed with the pinion gear 24, numeral 26 indicates reduction gears which are mounted coaxially with the reduction gears 25, numeral 27 indicates the load sheave bearing which is formed in the center of the frame 21, numeral 28 indicates bearings for reduction gear shafts which are disposed at positions outside the load sheave bearing 27 and at a given distance away from the load sheave bearing 27, numeral 29 indicates an upper hook mounting hole, numeral 30 indicates holes for mounting stud bolts, numeral 31 indicates stud bolts, numeral 32 indicates an upper hook, numeral 34 indicates a mechanical brake which is comprised of brake plates, a brake support, a ratchet wheel and a pawl, numeral 35 indicates a pinion shaft, numeral 36 indicates a manipulation lever, and numeral 37 indicates a casing.
In the above-mentioned conventional device, as shown in FIG. 6, the bearings 28 for the reduction gear which are formed in the frame 21 are, to ensure the support strength of the frame, disposed at a position of a given distance A away from the load sheave bearing 27. Accordingly, the distance between the axes of the pinion gear and each reduction gear and the distance between the axes of each reduction gear and the load gear respectively become large and the diameters of the respective gears become large. Eventually, the casing which covers these gears becomes large. Further, since the distance between the axes of the reduction gears 25 and 26 is large, it is necessary to insert the load gear 23 between the reduction gear 26 and the load sheave 22 to transmit the rotation of the reduction gear 26 to the load sheave. Further, since the load gear has a diameter which is larger than that of a bearing portion of the load sheave, it is necessary to assemble the pinion shaft having the load gear and the pinion gear after assembling the load sheave into the bearing portion of the frame.
As described above, in the conventional hoisting/pulling device, the distance between the axes of the reduction gear and the pinion gear and the distance between the axes of the reduction gear and the load gear are large and the respective gears are large in size. This prevents the hoisting/pulling device from being miniaturized. Further, it is necessary to assemble the pinion shaft having the load gear and the pinion gear after assembling the load sheave into the bearing of the frame, and hence, it is difficult to integrally form the load gear and the load sheave preliminarily. The present invention has been made to solve these drawbacks of the conventional device and provides a hoisting/pulling device which can make the whole device compact and lightweight and can reduce the number of parts and the man-hours for machining and assembling the device by making the distance between the axes of the reduction gears small and by making the outer diameter of the load gear equal to or smaller than the diameter of the bearing portion of the load sheave, and by integrally forming the load gear on the load sheave preliminarily.